We propose to use 31P NMR spectroscopy in conjunction with proton and CT imaging to correlate changes in the anatomical appearance of soft tissue sarcomas following pre-surgical chemotherapy with physiological and metabolic information obtained from 31P spectra localized to the sarcoma. Patients with soft tissue sarcomas will undergo NMR proton imaging and 31P spectroscopic examination of the tumor and surrounding tissue, prior to the initiation of chemotherapy, during its course, and just before final tumor resection. The soft tissue sarcomas tend to be large tumors in the extremities easily accessible to NMR examination. In addition, biopsy and tissue samples will be available for extraction, enabling us to compare the metabolites observed in the extracted in vitro spectra with those observed in vivo. Spectroscopic observations, as well as the information from the proton images, will be correlated with the histopathological results on tumor type and responses, and with the long term patient survival. In vivo observations will be made using chemical shift imaging (CSI) techniques. These techniques allow simultaneous observation of large volumes of tissue with a relatively high resolution (Z-3 cm for 31P). The data will be analyzed by an automatic software procedure which allows for peak identification and quantification with automatic baseline estimation (PIQABLE). This automatic data analysis will be invaluable in dealing with the large quantities of spectra produced by 3-dimensional CSI observations. Extensions of the CSI methodology are proposed which use the information in the free induction decay during the period the phase encoding gradients are on. Methods for presentation of spectroscopic data as overlays on the proton images will be developed in order to fully utilize the range of metabolic information provided by the CSI observations and facilitate correlation of spectroscopic and image data.